Highways particularly at night or when snow covered or when it is raining or snowing, are difficult for drivers of vehicles thereon to follow the edges of the highway or lanes thereof and it is conventional to paint lines longitudinally on the highway or mount projecting guides to indicate said edges or lanes, but such painted lines, or projections are difficult to see at night or when it is raining or snowing or are snow covered and known projections are damaged or removed when struck by snowplows clearing snow from the highway.
The following are know prior patents relating to such road markers;
U.S. Patent Nos: 1,640,830 1,668,288 1,661,242 1,676,843 1,688,409 2,345,644 1,707,951 2,541,460 1,766,841 2,779,240 1,773,488 3,091,977 1,804,389 3,175,935 1,901,333 3,240,132 1,903,869 3,298,555 1,915,179 3,308,584 1,948,335 3,312,156 1,949,295 3,340,779 1,961,580 3,362,305 1,981,206 3,409,344 2,005,170 3,417,676 2,108,370 3,418,896 2,121,961 3,442,187 2,318,722 3,575,773 3,693,511